Method of manufacturing a one-piece fan

ABSTRACT

A method of manufacturing a one-piece axial flow fan including the following steps: (1) forming one end of a cylindrical tube into a partially closed flat end surface having an opening therein of a predetermined diameter; (2) separating the wall of the cylinder into a predetermined number of arcuate sections; (3) bending the sections to extend radially outwardly from the partially closed end; (4) trimming off the edges of the radial extensions and portions of the bottom flat surface to form fan blades and a hub; and (5) twisting the blades to the desired final curvature, the final product being a one-piece axial flow fan having blades, each with one edge thereof on the same plane as the hub and a trailing edge bending away from the leading edge.

[72] Inventor Norman B. Vogt Utica, Mich. [21] Appl. No. 807,686 [22]Filed Mar. 17, 1969 [45] Patented Aug. 31, 1971 [73] Assignee GeneralMotors Corporation Detroit, Mich.

[54] METHOD OF MANUFACTURING A ONE-PIECE FAN 9 Claims, 8 Drawing Figs.

[52] U.S. Cl 29/1568 18, 1 13/1 16 D [51] l1nt.Cl 1132114 3/1141, B23p15/02,B23p 15/04 [50] Field of Search 29/1568 CF, 156.8 T, 156.8 B,156.8 P, 156.8 H, 159.01; 113/116D, 116 BB [56] References Cited UNITEDSTATES PATENTS 629,121 7/1899 Bicalky 113/116D 749,638 l/1904 Steiner113/116 D 2,235,461 3/1941 Miller 113/116D Primary Examiner-John F.Campbell Assistant ExaminerD0nald P. Rooney Attorneys-J5. W. Christen,A. M. Heiter and John P. Moran ABSTRACT: A method of manufacturing aone-piece axial flow fan including the following steps: (1) forming oneend of a cylindrical tube into a partially closed. flat end surfacehaving an opening therein of a predetermined diameter; (2) separatingthe wall of the cylinder into a predetermined number of arcuatesections; (3) bending the sections to extend radially outwardly from thepartially closed end; (4) trimming off the edges of the radialextensions and portions of the bottom flat surface to form fan bladesand a hub; and (5) twisting the blades to the desired final curvature,the final product being a 0ne-piece axial flow fan having blades, eachwith one edge thereofon the same plane as the hub and a trailing edgebending away from the leading edge.

PATENTEBAusm-mn 3501.876

44 mm? 15. fly; zhmzau ATTORNEY METHOD OF MANUFACTUIMNG A ONE-NECK; FAN

This invention relates to fluid propulsion devices, such as fans,propellers and the like, and, more particularly to a novel method ofmanufacturing a one-piece axial flow fan.

Present methods of manufacturing metal axial flow fans include suchmethods as forming a hub or spider, forming blades and then assemblingthe blades to the spider and balancing the assembly; or assemblingblades to form a hub as part of the blade material; or blanking the fanas one piece from sheet metal stock and shaping the blades thereof. Thelatter method results in considerable waste of material, thereby greatlyincreasing material cost.

Accordingly, a primary object of the invention is to provide a novelmethod of manufacturing a one-piece axial flow fan from a strip of sheetmetal which is formed into welded cylindrical tubing, or seamlesscylindrical tubing, with very little offal or waste material.

Another object of the invention is to provide a manufacturing methodwhich is simple and economical and which results in the production ofadurable and efficient finished product.

A further object of the invention is to provide a novel method ofmanufacturing a one-piece fan whose blades are variably spaced about anintegral hub and have trailing edges which terminate variable bladecurvatures, the variable spacing and curvatures serving to produce aminimal operative noise level.

Other objects and advantages of the invention will become apparent whenreference is made to the following specification and accompanyingdrawings wherein:

FIG. l is a top view of a sheet of metal material which may be employedin the invention;

FIG. an illustrate the results of the various manufacturing steps usedin the invention;

FIG. '7 illustrates a typical finished product resulting from theinvention; and

FIG. d is an end view taken along the plane ofthe line 8-4; of FIG, 7,and looking in the direction of the arrows.

Referring now to the drawings in greater detail, FIG. 1 illustrates aflat strip iii) of sheet metal which may be used in the novel methodembodied in the invention.

The metal strip it) is first formed into an open-ended cylinder l2 (FIG.2), the mating longitudinal edges of which are then fixedly attached toone another by any suitable method, such as welding, resulting in awelded seam M. The seam M is thereupon smoothed by any suitable method,for example, along its outer surface by scarfing or planishing, andalong its inner surface by being drawn over a mandrel. It is apparentthat the cylinder 112 could consist of seamless tubing of suitablediameter and thickness in lieu ofa welded cylinder.

The cylinder 112 may then be annealed, if necessary, after which one endof the cylinder i2 is formed in a forming die to include a radial end to(FIG. 3), resulting in an opening 17 remaining in the formed end 116which is substantially smaller then the inside diameter d of thecylinder 112. The forming die would normally include a die setcomprising an upper shoe and a lower shoe, and suitable tooling inserts.

The radial end it) of the cylinder 112 is further formed in a suitableforming die to produce a flat end surface 18 (FIG. d), which issubstantially perpendicular to the wall of the cylinder 12, The openingin the formed end l8 becomes a substantially smaller opening Ml duringthis operation. The latter opening Bill may be sized by being formedaround a pilot on the die set. As the openings l7 and 2b are madeprogressively smaller, the adjacent end portion ill would become thickerby virtue ofthe displacement of metal. This is desirable from thestandpoint of having a finished fan whose hub is thicker than itsblades.

The wall of the cylinder i2. is next separated (FIG. along predeterminedequally spaced lines 22a, 22b, 22c, 22d and 22e by any suitable shearingoperation, such as lancing. Preferably, the designated lines are alllanced simultaneously by utilizing a plurality of shearing tools, camsand cam drivers, the number thereof corresponding to the number ofseparations 22 required. Each separation 22 extends longitudinally alongthe cylindrical wall from the edge 24 of the open end to the inner face26 of the end 18, or to some predetermined distance there along, asillustraled in FIG, 5. The separations 22 result in a number ofarcuatewall segments 28, the total number thereof being determined by thenumber offon blades desired. Holes 29a, 29b, Mic, 29d and 2% may bepierced at the bottom end of each of the lanced edges of the separationsLilla, 22b, 22c, 22d and 22a, respectively, to prevent tearing in thisarea during subsequent operations.

Each of the arcuate wall sections 28 is next bent outwardly from theaxis of the cylinder l2, and flattened along the plane of the bottomsurface 18 so as to form flat extensions 30 (FIG. 6) extending radiallyoutwardly from the central opening Elli. This may be accomplished beusing a flared or tapered punch to start spreading the individual wallsegments 23 at their free ends E l. After some predetermined angle isreached between the outer surface of the wall segments and the plane ofthe bottom surface llll, a downwardly descending, flat upper die willcomplete the flattening process, the original arcuate shape of each wallsegment 2b being caused to assume a flat condition.

It may be noted by referring to FIGS. 5 and ti that, where some one linehas not been lanced the full length of the segments 28, such as line 22bin FIG. 5, when the segments 28d and 2&2 are flattened, they will tendto pull toward one another, the solid wall portion x" below the piercedhole 2% preventing a full spread therebetween. The result will be areduced included angle, such as angle *A" of FIG. t5, between adjacentsegments. It may be visualized that, when the wall of the cylinder l2.is lanced full length, such as represented at line 22a in HQ. 5, theflattening process will spread the segments 28a and 28b farther apart,as represented by angle in Fit]. 6. Thus it can be seen that bycontrolling the lengths of the lanced cuts, variable included angles maybe attained between segments during the flattening operation, the arcedsegments 28a, 23b, 28c, 28d and 28.? having been formed into flat radialextensions Ella, Elllb, Ellie, 30d and 3011, respectively.

After flattening, the extensions Ellla, 341th, 3531c, 36th! and Ellie,as well as portions of the flat end iii, are trimmed by any convenientmeans, such as with a trim die, producing the individual bladesrepresented by 32 in FIG. 6. it may be noted that each of the radialextensions Ill) includes sufficient area to form a fan blade 32 withvery little waste area, the latter being represented by 34. If desired,the hub I.D. Ml may be trimmed in the same operation as just described:however, as discussed above, the ll). 2b would have been formed around apilot on the die set during the operation described relative to Fifi. i.

As a result of the above lancing, flattening and trimming operations, afan structure is produced with a minimal amount of scrap materialinvolved, since the size of the cylinder l2 is selected such that eachsegment and 3% will include an area which is suitable for a particularblade 32. width plus sufficient stoclt for trimming, but without anexcessive amount of the latter.

It may be realized that if the segments Elba, 238b, Elle, 28d and werelanced to include different are lengths, and each lancing operation wereperformed along the full length of the cylinder l2, rather than variablelengths therealong, the fan blades 3?; could be individually located ontheir respective variable-width flat segments Elli such that variationin the angles "A," D, and .E." would result. However, such a techniquewould require a slightly larger cylinder for a given fan size than inthe steps described above.

After trimming, the resultant flat, one'piece structure would next beplaced in another forming die wherein the mating upper and lower shoesand/or tooling inserts would have curved mating surfaces formed inpockets or openings, there being one pocket for each blade 32. Theflattened fan structure would be placed therein such that: each of theblades 32 would be seated in some one of the pockets and pressed thereinto conform to the curvature of its respective pocket.

Obviously, the curvature need not be the same for all the blades 32. Theresult of this operation is illustrated in FIG. 8, wherein it may benoted that the leading edge 36 of a blade 32 remains on the same planeas the flat hub, while thetrailing edge 38 thereof terminates the bladesarcuate or curved shape.

The finished fan 40 is similar in appearance to that illustrated in FIG.7, with each of the variably spaced blades 32 having its ownpredetermined twist and/or curvature relative to the central hub portionthereof. The number of blades, however, could vary from thatillustrated. Hence, it is apparent that the fan resulting from theabove-described novel method includes desirable high-speed noiseabatement characteristics.

It should also be apparent that, in the method described above, aone-piece axial flow fan is produced with a negligible amount of scrapmaterial, representing substantial savings in material costs.

While but one general product has been illustrated and described asbeing manufactured by the above-described method, it should be apparentthat variations in the structure of the product could be attained by themethod described.

lclaim:

1. A method of producing a one-piece metal fan, said method comprisingforming one end of a cylindrical tube to include a flat end surfacehaving an opening therein of a predetermined diameter, longitudinallycutting said formed cylindrical tube to produce a plurality of adjacentarcuate segments, said arcuate segments being unequally spaced andseparated by lanced edges extending the full length of the remainingwall of said cylindrical tube after said flat end has been formedthereon, bending said arcuate segments outwardly so as to cause saidsegments to'become flattened, and to extend substantially radially fromsaid flat end surface, trimming said segments and said flat end surfaceto form a hub with integral flat fan blades extending therefrom, saidflat fan blades being variably spaced with respect to one another, andforming predetermined blade curvatures on said fan blades.

2. A method of manufacturing a one-piece metal fan, said methodcomprising the following steps:

a. forming a rectangular piece'of sheet metal material of predetermineddimensions into a cylindrical shape;

b. joining the longitudinal mating edges thereof as a seam to produce acylindrical tube;

c. smoothing said seam;

d. forming one end of said cylindrical tube to produce a flat endsurface having an opening therein of a predetermined diameter;

c. cutting the wall of said cylindrical tube into a predetermined numberof adjacent longitudinal arcuate sections;

f. bending said sections outwardly so as to cause said sections tobecome flattened and to lie on the plane of said flat end surface; g.trimming of the edges of said sections and a portion of said flat endsurface to form a hub with integral fan blades extending therefrom; andforming the individual blades to include predetermined blade curvaturesthereon.

3. A method of manufacturing a one-piece metal fan, said methodcomprising the following steps:

a. forming one end of a cylindrical tube to produce a flat end surfacehaving an opening therein ofa predetermined diameter;

b. separating the wall of said cylindrical tube into a predeterminednumber of adjacent longitudinal arcuate sections by cutting said wall ofsaid cylindrical tube such that the resultant cut edges between adjacentsections are variable in length;

c. bending said sections outwardly so as to cause said sections tobecome flattened and to lie on the plane of said flat end surface;

d. trimming off the edges of said sections and a portion of said flatend surface to form a hub with integral fan blades extending therefrom;and e. forming the individual blades to include predetermined bladecurvatures thereon.

4. The method described in claim 3, wherein a hole is pierced at thebottom of each lanced separation.

5. The method described in claim 3, wherein said arcuate sections areequally spaced prior to said bending operation.

6. The method described in claim 5, wherein said fan blades are variablyspaced from one another after said trimming operation.

7. A method of producing a one-piece metal fan from a cupshaped memberhaving a base portion and a circular sidewall portion, said methodcomprising longitudinally cutting said sidewall portion of saidcup-shaped member into a plurality of adjacent arcuate segments of saidcircular sidewall portion, bending said circular sidewall portion andsaid arcuate segments outwardly substantially into the plane of saidbase portion to form a substantially flat blank, trimming said blank toform said base portion into a hub and said arcuate segments intointegral flat fan blades integrally extending substantially radiallyfrom said base portion and being variably spaced with respect to oneanother, and forming predetermined blade pitch curvatures on said fanblades.

8. A method of producing a one-piece metal fan, said method comprisingforming a cup-shaped member having a substantially flat bottom portionand a circular wall portion extending therefrom, longitudinally cuttingsaid circular wall portion of said cup-shaped member to form a pluralityof adjacent arcuate segments, said arcuate segments being unequallyspaced and separated by adjacent edges extending the full length of saidwall portion of said cup-shaped member, bending said arcuate segmentsoutwardly so as to cause said segments to become flattened and to extendsubstantially radially from said bottom portion, trimming said segmentsand said bottom portion of said cup-shaped member to form a hub withintegral planar fan blades extending therefrom and being variably spacedwith respect to one another, and forming predetermined blade curvatureson said fan blades.

9. A method of manufacturing a one-piece metal fan, said methodcomprising the following steps:

a. forming a cup-shaped member having a substantially flat bottomportion and a circular wall portion extending therefrom;

. cutting said wall portion of said cup-shaped member into apredetermined number of adjacent longitudinal arcuate sections such thatthe resultant edges therebetween are variable in length;

. bending said arcuate sections outwardly so as to cause said arcuatesections to become flattened and to lie substantially on the plane ofsaid flat bottom portion;

trimming off said edges of said flattened sections and a portion of saidbottom portion to form a hub with integral fan blades extendingsubstantially radially therefrom; and

. forming the individual fan blades to include predetermined bladecurvatures thereon.

1. A method of producing a one-piece metal fan, said method comprisingforming one end of a cylindrical tube to include a flat end surfacehaving an opening therein of a predetermined diameter, longitudinallycutting said formed cylindrical tube to produce a plurality of adjacentarcuate segments, said arcuate segments being unequally spaced andseparated by lanced edges extending the full length of the remainingwall of said cylindrical tube after said flat end has been formedthereon, Bending said arcuate segments outwardly so as to cause saidsegments to become flattened, and to extend substantially radially fromsaid flat end surface, trimming said segments and said flat end surfaceto form a hub with integral flat fan blades extending therefrom, saidflat fan blades being variably spaced with respect to one another, andforming predetermined blade curvatures on said fan blades.
 2. A methodof manufacturing a one-piece metal fan, said method comprising thefollowing steps: a. forming a rectangular piece of sheet metal materialof predetermined dimensions into a cylindrical shape; b. joining thelongitudinal mating edges thereof as a seam to produce a cylindricaltube; c. smoothing said seam; d. forming one end of said cylindricaltube to produce a flat end surface having an opening therein of apredetermined diameter; e. cutting the wall of said cylindrical tubeinto a predetermined number of adjacent longitudinal arcuate sections;f. bending said sections outwardly so as to cause said sections tobecome flattened and to lie on the plane of said flat end surface; g.trimming of the edges of said sections and a portion of said flat endsurface to form a hub with integral fan blades extending therefrom; andh. forming the individual blades to include predetermined bladecurvatures thereon.
 3. A method of manufacturing a one-piece metal fan,said method comprising the following steps: a. forming one end of acylindrical tube to produce a flat end surface having an opening thereinof a predetermined diameter; b. separating the wall of said cylindricaltube into a predetermined number of adjacent longitudinal arcuatesections by cutting said wall of said cylindrical tube such that theresultant cut edges between adjacent sections are variable in length; c.bending said sections outwardly so as to cause said sections to becomeflattened and to lie on the plane of said flat end surface; d. trimmingoff the edges of said sections and a portion of said flat end surface toform a hub with integral fan blades extending therefrom; and e. formingthe individual blades to include predetermined blade curvatures thereon.4. The method described in claim 3, wherein a hole is pierced at thebottom of each lanced separation.
 5. The method described in claim 3,wherein said arcuate sections are equally spaced prior to said bendingoperation.
 6. The method described in claim 5, wherein said fan bladesare variably spaced from one another after said trimming operation.
 7. Amethod of producing a one-piece metal fan from a cup-shaped memberhaving a base portion and a circular sidewall portion, said methodcomprising longitudinally cutting said sidewall portion of saidcup-shaped member into a plurality of adjacent arcuate segments of saidcircular sidewall portion, bending said circular sidewall portion andsaid arcuate segments outwardly substantially into the plane of saidbase portion to form a substantially flat blank, trimming said blank toform said base portion into a hub and said arcuate segments intointegral flat fan blades integrally extending substantially radiallyfrom said base portion and being variably spaced with respect to oneanother, and forming predetermined blade pitch curvatures on said fanblades.
 8. A method of producing a one-piece metal fan, said methodcomprising forming a cup-shaped member having a substantially flatbottom portion and a circular wall portion extending therefrom,longitudinally cutting said circular wall portion of said cup-shapedmember to form a plurality of adjacent arcuate segments, said arcuatesegments being unequally spaced and separated by adjacent edgesextending the full length of said wall portion of said cup-shapedmember, bending said arcuate segments outwardly so as to cause saidsegments to become flattened and to extend substantially radially fromsaid bottom portion, trimming said segments and said bottom portion ofsaid cuP-shaped member to form a hub with integral planar fan bladesextending therefrom and being variably spaced with respect to oneanother, and forming predetermined blade curvatures on said fan blades.9. A method of manufacturing a one-piece metal fan, said methodcomprising the following steps: a. forming a cup-shaped member having asubstantially flat bottom portion and a circular wall portion extendingtherefrom; b. cutting said wall portion of said cup-shaped member into apredetermined number of adjacent longitudinal arcuate sections such thatthe resultant edges therebetween are variable in length; c. bending saidarcuate sections outwardly so as to cause said arcuate sections tobecome flattened and to lie substantially on the plane of said flatbottom portion; d. trimming off said edges of said flattened sectionsand a portion of said bottom portion to form a hub with integral fanblades extending substantially radially therefrom; and e. forming theindividual fan blades to include predetermined blade curvatures thereon.